System control device and method of system control

ABSTRACT

The present invention includes a hunting determination unit configured to determine whether hunting has occurred or not for each of control devices in a power transmission and distribution system based on a control history of the control devices, a time constant calculation unit configured to calculate an adjustment time constant in which a time constant of the control device having state information indicating a state of the control device, with a high significance level, is increased, when the hunting determination unit determines that the hunting has occurred in one or more of the control devices, and a time constant transmission unit configured to transmit the adjustment time constant to the control device.

TECHNICAL FIELD

The present invention relates to a technique for controlling a controldevice.

BACKGROUND ART

In order to maintain the voltage distribution/current distribution of apower transmission and distribution system within an appropriate range,Patent Document 1 discloses a technique for dynamically controlling thetime constants of a plurality of control devices installed in a powertransmission and distribution system. When controlling the timeconstants of a plurality of control devices in such a power transmissionand distribution system, as a result of control of the time constants,coordination among the control devices is failed, leading to occurrenceof over-control, and hunting in which voltage and current vibrateoccurs. It is generally known that, when the hunting occurs, increasingthe time constant of the control device in which the hunting hasoccurred reduces the number of operations (in the case where the controldevice is a Load Ratio Control Transformer (LRT), reduces the number oftaps) of each control device, thereby eliminating the hunting.

PRIOR ART DOCUMENTS Patent Documents

-   [Patent Document 1] Japanese Patent Application Laid-Open No.    2012-182897

SUMMARY Problem to be Solved by the Invention

In the prior art, when hunting occurs in each control device in a powertransmission and distribution system, the time constant of the controldevice in which hunting has occurred is individually changed. In thiscase, every time hunting occurs, the process of suppressing the huntingby increasing the time constant of the control device in which thehunting has occurred is repeated. Accordingly, when the adjustment ofthe time constant of each control device is repeated with coordinationfailure in the power transmission and distribution system, the timeconstant of a specific control device may become too large and deviationoccurs. For example, the number of operations (the number of LRT taps orthe like) varies among control devices in the power transmission anddistribution system.

Accordingly, if the numbers of operations are varied, the state of thecontrol devices is likely to be varied when viewed in the whole powertransmission and distribution system. Specifically, deviation occurs inthat deterioration is concentrated on a specific control device (acontrol device with the larger number of operations tends todeteriorate) and in that power loss is concentrated on a specificcontrol device (a control device with the larger number of operationstends to lose more power).

From the viewpoint of reducing operational costs, it is desirable thatthe control devices in the power transmission and distribution systemare evenly deteriorated, and it is desirable to prevent deviation thatfurther increases the number of operations of a control device withhaving large power loss. An object of the invention is to prevent thedeviation of the state of the control devices in the power transmissionand distribution system, while suppressing the hunting of each controldevice in the power transmission and distribution system.

Means to Solve the Problem

In order to solve the above-described problems and achieve the object,the system control device according to the present invention includes ahunting determination unit configured to determine whether hunting hasoccurred or not for each of control devices in a power transmission anddistribution system based on a control history of the control devices, atime constant calculation unit configured to calculate an adjustmenttime constant in which a time constant of the control device havingstate information indicating a state of the control device, with a highsignificance level, is increased, when the hunting determination unitdetermines that the hunting has occurred in one or more of the controldevices, and a time constant transmission unit configured to transmitthe adjustment time constant to the control device.

Effects of the Invention

While suppressing the hunting of the control devices in the powertransmission and distribution system, the state can be prevented frombeing deviated.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A block diagram illustrating a configuration example of a systemcontrol device according to Embodiment 1.

FIG. 2 A flowchart illustrating a flow of processes for adjustment timeconstant calculation of the system control device according toEmbodiment 1.

FIG. 3 A flowchart illustrating a flow of processes until a process thecontrol device according to Embodiment 1 transmits device information tothe system control device.

FIG. 4 A flowchart illustrating a flow of processes from a process afterthe control device according to Embodiment 1 receives an adjustment timeconstant from the system control device.

FIG. 5 A hardware configuration diagram illustrating a configuration ofa control plan creation device.

FIG. 6 A flowchart illustrating a flow of processes for adjustment timeconstant calculation of the system control device according toEmbodiment 2.

FIG. 7 A flowchart illustrating a flow of processes until a process thecontrol device according to Embodiment 2 transmits device information tothe system control device.

FIG. 8 A flowchart illustrating a flow of processes from a process afterthe control device according to Embodiment 2 receives an adjustment timeconstant from the system control device.

FIG. 9 A block diagram illustrating a configuration example of a systemcontrol device according to Embodiment 3.

FIG. 10 A flowchart illustrating a flow of processes for adjustment timeconstant calculation of the system control device according toEmbodiment 3.

FIG. 11 A flowchart illustrating a flow of processes until a process apower consumption facility according to Embodiment 3 transmits consumedpower to the system control device.

FIG. 12 A flowchart illustrating a flow of processes until a process apower generation facility according to Embodiment 3 transmits generatedpower to the system control device.

FIG. 13 A flowchart illustrating a flow of processes until a process acontrol device according to Embodiment 3 transmits device information tothe system control device.

FIG. 14 A flowchart illustrating a flow of processes from a processafter the control device according to Embodiment 3 receives anadjustment time constant from the system control device.

FIG. 15 A flowchart illustrating a flow of processes until a process acontrol device according to Embodiment 4 transmits device information toa system control device.

FIG. 16 A flowchart illustrating a flow of processes for adjustment timeconstant calculation of the system control device according toEmbodiment 4.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a system control device 200 and a system control methodaccording to Embodiments of the present invention will be described indetail referring to the drawings. Note that the present invention is notlimited to Embodiments.

Embodiment 1

FIG. 1 is a block diagram illustrating one configuration example of asystem control device 200 and system control devices 300 within a powertransmission and distribution system 100 according to Embodiment 1. Thesystem control device 200 includes a device information reception unit1, a hunting determination unit 2, a device rank calculation unit 3, atime constant calculation unit 4, and a time constant transmission unit5. The control device 300 includes a device information storage unit 6,a device information transmission unit 7, a time constant reception unit8, and a time constant adjustment unit 9.

The system control device 200 is a device that adjusts the timeconstants of the control devices 300 in the power transmission anddistribution system. Here, the control devices 300 include, for example,an LRT installed in a substation, a Step Voltage Regulator (SVR)installed on a distribution line, and a voltage regulator such as aDC/DC converter for DC transmission and distribution, and so forth. Thecontrol devices 300 periodically regulate the voltage in order to keepthe voltage within a specified value. Each of the control devices 300has a time constant. Due to this time constant, the control device 300sets the frequency of voltage regulation with a temporal buffer.

That is, by adjusting the time constant, the frequency of voltageregulation of the control device 300 can be changed. As the timeconstant increases, the frequency of adjustment decreases, and as thetime constant decreases, the frequency of adjustment increases.Specifically, when the control device 300 is an LRT, the number of tapsdecreases as the time constant increases, and the number of tapsincreases as the time constant decreases. Such control using a timeconstant is known as the prior art.

Each unit of the system control device 200 will be described. The deviceinformation reception unit 1 of the system control device 200 receivesdevice information transmitted from each control device 300. Here, thedevice information includes a control history at each time of thecontrol device 300 and state information of the control device 300 ateach time of the control device 300. For example, the device informationis information on devices such as tap switching times, a tap voltage,and a control target voltage. Here, the state information is informationrepresenting the state of the control device 300, and is information ona deterioration progress degree, power loss and the like. Stateinformation with a high significance level indicates that thedeterioration progress degree has progressed or power loss is large, andthe state information with a low significance level indicates that thedeterioration progress degree has not progressed or power loss is small.

In Embodiment 1, although the deterioration progress degree, which isthe state information on each device, is provided as device information,the device information is not limited thereto. The deteriorationprogress degree may be calculated from device information such as thetap switching times and the voltage information of the device. Thecalculation of the deterioration progress degree may be executed by thecontrol device 300 or may be executed by the system control device 200,and is not limited to either device.

Based on the control history received by the device informationreception unit 1, the hunting determination unit 2 of the system controldevice 200 determines whether or not hunting has occurred for eachcontrol device 300. Various methods for determining hunting are known.For example, hunting can be determined based on whether the tap voltageor the control target voltage vibrates in a predetermined period. Also,for example, hunting can be determined by calculating the amplitude ateach frequency with respect to the tap voltage or the control targetvoltage by using the discrete Fourier transform, and determining whetherthe amplitude at a predetermined frequency component exceeds apredetermined value.

The device rank calculation unit 3 of the system control device 200calculates rank order for adjusting the time constants of respectivecontrol devices 300 so that the progress of deterioration of the controldevices 300 is leveled while suppressing the hunting of each controldevice 300 based on the deterioration progress degree received by thedevice information reception unit 1 and a hunting determination resultof the hunting determination unit 2.

In Embodiment 1, although the rank order for the control devices 300subject to control the time constants is determined based on thedeterioration progress degrees, the determination of the rank order isnot limited thereto and the device rank calculation unit 3 performsranking based on the state information. As the state information, therank order may be determined based on the power loss to be described indetail in Embodiment 2.

It is desired to adjust that the time constant of the control device 300of which deterioration progress degree has progressed more to bepreferentially increased so as not to promote deterioration of thecontrol device 300 of which deterioration progress degree has progressedeven more. Therefore, when the hunting determination unit 2 determinesthat hunting has occurred in one or more control devices 300, the devicerank calculation unit 3 ranks the control devices 300 in the order ofprogression of the deterioration progress degree. Here, thedeterioration progress degree of a control device j at the current timeis set as d(j).

For example, when the control device 300 is the LRT, the deteriorationprogress degree d(j) is a value obtained by dividing the cumulativevalue of tap switching times by the average value of the total tapswitching times during the period from the installation to the failureor replacement. The control devices 300 are ranked in the order ofprogression of the deterioration progress degree d(j).

Further, for example, when the control device 300 is a DC/DC converter,the deterioration progress degree d(j) is a value obtained by dividingthe output power amount of the DC/DC converter by the average value ofthe total output power amount during the period from the installation tothe failure or replacement. The control devices 300 are ranked in theorder of progression of the deterioration progress degree d(j). Theaverage values described here may be calculated in advance based on theoperation record of the control device 300.

Here, hunting can be prevented by increasing the time constant, however,on the other hand, there has been a problem in that if the time constantis excessively increased, the control response will be delayed and dueto rapidly changing power such as power load and photovoltaic powergeneration, the voltage distribution and current distribution cannot bemaintained within an appropriate range. For this reason, it is desirableto adjust the time constant to be small within a range where huntingdoes not occur so that the time constant does not become excessivelylarge.

Therefore, when no hunting has occurred in the control device 300, it isdesirable to adjust a large time constant as small as possible within arange where hunting does not occur. Therefore, when the huntingdetermination unit 2 determines that no hunting has occurred in one ormore control devices 300, the device rank calculation unit 3 furtherranks the control devices 300 in the reversed order of progression ofthe deterioration progress degree.

The time constant calculation unit 4 of the system control device 200calculates the time constant of each control device 300 based on thedetermination result of the hunting determination unit 2 and the rankorder determining the time constant of each control device 300calculated by the device rank calculation unit 3. If hunting hasoccurred even with one control device 300, the highest priority is tosuppress hunting. To this end, the time constant of any control device300 in the power transmission and distribution system 100 need beincreased.

When the hunting determination unit 2 determines that hunting hasoccurred in one or more control devices 300, the time constantcalculation unit 4 calculates an adjustment time constant in which thetime constant of the control device 300 selected according to the rankorder is increased.

Specifically, the time constant calculation unit 4 calculates a newadjustment time constant in which the time constant of the controldevice 300, which is determined to be the most progressed indeterioration, is increased by a predetermined time (for example, 1second) based on the rank order of the deterioration progress degree.Giving the priority to the control device 300 having the higher rank,the time constant is increased; therefore, it is expected that thedeterioration progress degree d(j) will be suppressed from progressingwhile hunting is suppressed, and the deterioration progress degree d(j)will be leveled.

Meanwhile, when the hunting determination unit 2 determines that nohunting has occurred in one or more control devices 300, the timeconstant calculation unit 4 calculates a new adjustment time constant inwhich the time constant of the control device 300, which is determinedto be the least progressed in deterioration, is decreased by apredetermined time (for example, 1 second) based on the deteriorationprogress degree. Giving the priority to the control device 300 havingthe higher rank, the time constant is decreased; therefore, it isexpected that the time constant will be prevented from being excessivelylarge, and the deterioration progress degree d(j) will be leveled.

Such calculation of the adjustment time constant is repeatedly executedwhen the hunting determination unit 2 determines that hunting hasoccurred in one or more control devices 300. In Embodiment 1, control isnot performed so as to update the time constant of the control device300 in which hunting has occurred, and the time constants are updatedfor any control devices 300 in the power transmission and distributionsystem, even if no hunting has occurred. In particular, control isperformed so as to change the time constant of the control device 300 ofwhich deterioration progress degree has progressed.

In other words, by changing the time constant of the control devices 300other than the control device 300 in which hunting has occurred,coordination with other control devices 300 in the same system can beachieved, and hunting of the control device 300 in which hunting hasoccurred can be stopped. If hunting does not stop even after the timeconstant is changed, or if hunting occurs in another control device 300by changing the time constant, hunting of one or more control devices300 again is determined to have occurred.

In Embodiment 1, although the adjustment time constant of the controldevice 300 of the most progressed in deterioration is calculated basedon the rank order of the deterioration progress degree, the adjustmenttime constant may be calculated by selecting the control device 300 ofthe most progressed in deterioration (the control device 300 having thestate information with the highest significance level) without executingthe calculation of the rank order. When calculating the adjustment timeconstant of the control device 300 of the least progressed indeterioration, the adjustment time constant may be calculated byselecting the control device 300 of the least progressed indeterioration (the control device 300 having the state information withthe lowest significance level) without executing the calculation of rankorder.

Here, although wordings “the control device 300 of the most progressedin deterioration (the control device 300 having the state informationwith the highest significance level)” and “the control device 300 of theleast progressed in deterioration (the control device 30 having thestate information with the lowest significance level)” are used above,as long as the control device 300 is progressed in deterioration (thecontrol device 300 having the state information with a high significancelevel) or is not progressed in deterioration (the control device 300having the state information with a low significance level),deterioration progressed and the state information are not limited tothe highest or lowest.

In addition, when the process is repeated, instead of calculating theadjustment time constant of the control device 300 of whichdeterioration progress degree has most progressed (the control device300 having the state information with the highest significance level)every time, control may be performed so that the adjustment timeconstant of the control devices 300 is calculated in the order ofprogression of the deterioration progress degree of the control devices300 (the control device 300 having the state information with a highsignificance level).

More specifically, each time the time constant of the control device 300is updated with the adjustment time constant, the hunting determinationunit 2 determines whether hunting has occurred or not, each time thehunting determination unit 2 determines that hunting has occurred in oneor more control devices 300, the time constant calculation unit 4calculates the adjustment time constants in which the time constants ofthe control devices 300 in the rank order of the control device 300having the state information with higher significance level, and thetime constant transmission unit 5 transmits the calculated adjustmenttime constant to the corresponding control device 300, and updates thetime constant of the control device 300 with the adjustment timeconstant.

In addition, each time the hunting determination unit 2 determines thatno hunting has occurred in one or more control devices 300, theadjustment time constants that are decreased in the time constants ofthe control devices 300 are calculated in the rank order of the controldevice 300 having the state information with lower significance level.The time constant transmission unit 5 transmits the calculatedadjustment time constant to the corresponding control device 300, andupdates the time constant of the control device 300 with the adjustmenttime constant.

Subsequently, each unit of the system control device 300 will bedescribed. The device information storage unit 6 of the control device300 stores the control history at each time of the control device 300and the device information that is the state information of thedeterioration progress degree of the control device 300 at each time ofthe control device 300. The control history of the control device 300is, for example, the tap voltage at each time when the control device300 is an LRT, and the control target voltage, control target current,or control target power at each time when the control device 300 is aDC/DC converter.

The deterioration progress degree of the control device 300 isrepresented by, for example, a cumulative value of the tap switchingtimes when the control device 300 is an LRT. Or, when the control device300 is a DC/DC converter, the deterioration progress degree isrepresented by a cumulative value of output power amount (outputpower×time) as information for indicating that large power has beenoutput for a long time. In the case of power electronics equipment,outputting a large amount of power for a long time deteriorates theequipment.

In Embodiment 1, a power transmission and distribution system isassumed, and plurality of control devices 300 are assumed to be providedin the system. Note that, when controlling a system in which an ACsystem and a DC system are mixed, the control devices 300 of a pluralityof types are present with an LRT and a DC/DC converter being mixed.

The device information transmission unit 7 of the control device 300transmits the device information stored in the device informationstorage unit 6 to the system control device 200.

The time constant reception unit 8 of the control device 300 receivesthe adjustment time constant of the control device 300 transmitted fromthe system control device 200.

The time constant adjustment unit 9 of the control device 300 updatesthe time constant of the control device 300 based on the adjustment timeconstant received by the time constant reception unit 8. Next, a flow ofprocesses of the system control device 200 according to Embodiment 1will be described with reference to the flowcharts of FIGS. 2, 3, and 4.

FIG. 2 is a flowchart illustrating a flow of processes for adjustmenttime constant calculation of the system control device 200 according toEmbodiment 1. This flowchart illustrates the processes from receivingthe device information from the control device 300, determining huntinghas occurred or not, to calculating an adjustment time constant.Although not clearly illustrated in the flowchart, this processing isrepeatedly operated when the hunting determination unit 2 determinesthat no hunting has occurred in one or more control devices 300. InEmbodiment 1, the adjustment time constant is calculated taking thedeterioration progress degree into consideration.

FIG. 3 is a flowchart illustrating a flow of processes until a process acontrol device 300 according to Embodiment 1 transmits the deviceinformation to the system control device 200.

FIG. 4 is a flowchart illustrating a flow of processes from a processafter the control device 300 according to Embodiment 1 receives theadjustment time constant from the system control device 200.

In the control device 300, the device information storage unit 6 storesthe device information of the control device 300 such as the controlhistory, the deterioration progress degree and the like (Step S101). Thedevice information transmission unit 7 acquires the stored deviceinformation and transmits the information to the system control device200 (Step S102).

Next, in the system control device 200, the device information receptionunit 1 receives the device information transmitted from each controldevice 300, and outputs the received device information to the huntingdetermination unit 2 and the device rank calculation unit 3 (Step S103).The control information is received again when the time constant of thecontrol device 300 is updated with the calculated adjustment timeconstant.

The hunting determination unit 2 acquires each device information,determines whether or not hunting has occurred in each control device300 based on the control history of the acquired device information, andoutputs the determination result to the device rank calculation unit 3and the time constant calculation unit 4 (Step S104).

The device rank calculation unit 3 acquires the device information andthe hunting determination result (Step S105), and when the huntingdetermination result indicates that the determination that hunting hasoccurred in one or more of each control device 300 has made, the devicerank calculation unit 3 ranks the control devices 300 in the order ofprogression of the deterioration progress degree (Step S106).

Meanwhile, when the device rank calculation unit 3 determines that thehunting determination result indicates that no hunting has occurred inone or more control devices 300, the device rank calculation unit 3ranks the control devices 300 in the reversed order of progression ofthe deterioration progress degree. The device rank calculation unit 3outputs the device rank order to the time constant calculation unit 4(Step S108). In Embodiment 1, ranking when hunting has occurred and whenno hunting has occurred is reversed, the methods are not limitedthereto. However, ranking may be the same and, as described below, theorder of selection of the control device 300 by the time constantcalculation unit 4 may be reversed. The methods are not limited. Whenthe ranking is the same, reference of the hunting determination resultis not required in Step S107.

The time constant calculation unit 4 acquires the hunting determinationresult and the device rank (Step S109) and when the huntingdetermination result is the one determined that hunting has occurred inone or more control devices, the time constant calculation unit 4calculates the adjustment time constant in which the time constant ofthe control device 300 selected according to the acquired rank order isincreased. Specifically, an adjustment time constant obtained byincreasing the time constant of the control device 300 having thehighest rank order of deterioration progress degree by a predeterminedtime is calculated (Step S110).

Here, although the deterioration progress degrees are ranked in theorder of progression when the hunting result is the one determined thathunting has occurred in one or more devices to increase the timeconstant of the control device 300 having the highest rank order ofdeterioration progress degree by a predetermined time, the method is notlimited thereto, the method of determining the control device 300 havingthe most progressed deterioration progress degree is not limited.

Also, although based on the rank order of deterioration progress degreethat has been assigned when it is determined that hunting has occurredin one or more control devices 300, the device rank calculation unit 3calculates an adjustment time constant of the control device 300 havingthe highest rank order, it is not limited thereto, and it may alsocontrol such that the adjustment time constant is calculated byselecting the control device 300 having the progressed deteriorationprogress degree (state information with a high significance level)without calculating the rank order. In this case, it is even morepreferable to select the control device 300 having the highestdeterioration progress degree (state information with the highestsignificance level) and control to calculate the adjustment timeconstant.

Meanwhile, when it is determined that no hunting has occurred in one ormore control devices 300, the time constant calculation unit 4calculates an adjustment time constant obtained by decreasing the timeconstant of the control device 300 having the highest rank order of thedeterioration progress degree calculated when it is determined that nohunting has occurred in one or more control devices 300 by apredetermined time (Step S111).

Here, although, when it is determined that no hunting has occurred inone or more control devices 300, the time constant calculation unit 4ranks the deterioration progress degrees in ascending order anddecreases the time constant of the control device 300 having the highestrank order of the deterioration progress degree by a predetermined time,the method is not limited thereto, the method of determining the controldevice 300 having the least progressed deterioration progress degree isnot limited. For example, in the device rank calculation unit 3, rankingmethods when hunting has occurred and when no hunting has occurred, maybe the same and control is performed so as to decrease the timeconstants of the control devices 300 in the reversed order of this rankorder.

Also, although based on the rank order of deterioration progress degreethat has been assigned when it is determined that no hunting hasoccurred in one or more control devices 300, the device rank calculationunit 3 calculates an adjustment time constant of the control device 300having the highest rank order, it is not limited thereto, and it mayalso control such that the adjustment time constant is calculated byselecting the control device 300 having the less progresseddeterioration progress degree (state information with a low significancelevel) without calculating the rank order. In this case, it is even morepreferable to select the control device 300 having the least progresseddeterioration progress degree (state information with the lowestsignificance level) and control to calculate the adjustment timeconstant.

The time constant calculation unit 4 outputs the adjustment timeconstant calculated for each control device 300 to the time constanttransmission unit 5. The time constant transmission unit 5 acquires theadjustment time constant of each control device 300, transmits theadjustment time constant to the control device 300 to have the timeconstant of the control device 300 updated (Step S112).

Finally, in the control device 300, the time constant reception unit 8receives the adjustment time constant transmitted from the systemcontrol device 200, and outputs the received adjustment time constant tothe time constant adjustment unit 9 (Step S113). The time constantadjustment unit 9 acquires the adjustment time constant, and updates thetime constant of the control device 300 based on the acquired adjustmenttime constant (Step S114).

When the control information is received from the control device 300every time the time constant of the control device 300 is updated withthe adjustment time constant, the hunting determination unit 2 furtherdetermines whether hunting has occurred or not, and the processing ofFIG. 2 is repeated.

In this repeating processing, the time constant calculation unit 4 maycontrol such that, every time the hunting determination unit 2determines that hunting has occurred in one or more of the controldevices 300, the time constant calculation unit 4 calculates theadjustment time constants in which the time constants are increased inthe order of progression of the deterioration progress degree of thecontrol devices 300 (state information with a high significance level),and every time the hunting deterioration unit 2 determines that nohunting has occurred in one or more of the control devices 300, the timeconstant calculation unit 4 calculates an adjustment time constant inwhich the time constants are decreased in the reversed order ofprogression of the deterioration progress degree of the control devices300 (state information with a low significance level).

The time constant transmission unit 5 transmits the calculatedadjustment time constant to the corresponding control device 300, andupdates the time constant of the control device 300 every time theadjustment time constant is calculated. in this manner, calculation andupdating of the adjustment time constant may be continued in turn.

In Embodiment 1, although the adjustment time constant is calculated byincreasing or decreasing by a predetermined time, the calculation is notlimited thereto, and the method of increasing is not limited. Further,in the case where the time constant is decreased, the time constant maybe decreased, and the method of decreasing is not limited.

Further, in Embodiment 1, although, control is performed so as to changethe time constant of the control device 300 having the highest rankorder of the deterioration progress degree, a case where the controldevice 300 to be controlled not being the highest rank can beconceivable. For example, a case can be conceivable in which the upperlimit value and the lower limit value of the time constant for eachcontrol device 300 are stored in the device information storage unit 6,and when the adjustment time constant to be calculated falls below thestored lower limit value or exceeds the stored upper limit value whenchanging the time constant of the control device 300 with the highestdevice rank, the time constant of the control device 300 of the nextrank is changed.

In Embodiment 1, although, control is performed such that the timeconstant of the control device 300 having the highest degree ofdeterioration progress degree is changed in order, the time constants ofa plurality of control devices 300 are weighted by the rank order can beperformable as a variation. For example, it can be conceivable in thatfor the control device 300 with the highest device rank, the timeconstant is changed by 3 seconds, for the control device 300 with thesecond highest rank, the time constant is changed by 2 seconds, and forthe control device 300 with the third highest rank, the time constant ischanged by 1 second.

In Embodiment 1, although, control is performed so as to increase thetime constant for the higher deterioration progress degree, it is alsoconceivable to control so that the time constant is increased for thesmaller time constant. However, the degree of progress of deteriorationdepends on factors other than the number of operations; therefore, inEmbodiment 1, the time constant is adjusted by referring to thedeterioration progress degree alone.

FIG. 5 is a hardware configuration diagram illustrating a configurationof the system control device 200. The system control device 200 includesan input interface 201, a Central Processing Unit (CPU) 202, a storagedevice 203, and an output interface 204. An interface is hereinafterreferred to as IF.

The adjustment time constant is stored in the storage device 203, andthe functions of the hunting determination unit 2, the device rankcalculation unit 3, the time constant calculation unit 4, and the likeare realized by executing a program by the CPU 202. The deviceinformation reception unit 1 includes an input IF. The time constanttransmission unit 5 includes an output IF, and the created adjustmenttime constant is output from the output IF.

The IF includes a wired port such as a cable port, a USB port, a directconnection port, and a wireless network port. The storage device 203includes a storage medium such as an HDD, an SSD, and a flash memory.

As described above, in Embodiment 1, the deterioration progress degreeof the control device 300 is stored in the device information storageunit 6, and the device rank calculation unit 3 ranks the control devices300 based on the deterioration progress degree of each control device300. The time constant calculation unit 4 selects the control device 300which is the target for the change of the time constant and calculatesthe adjustment time constant of the control device 300 based on thecalculated device order. Accordingly, in the whole system, deteriorationdue to load deviation on a specific control device 300 is suppressedfrom becoming fast while suppressing hunting in each control device 300.

Embodiment 2

Although Embodiment 2 has the same configuration as that of FIG. 1, thedifference lies in that the device rank calculation unit 3 ranks thecontrol devices 300 based on the power loss. In that case, as deviceinformation to be stored in the device information storage unit 6, apower loss generated when power is converted in the LRT or the DC/DCconverter may be stored. This power loss may be calculated from thedevice information. The calculation of the power loss may be executed bythe control device 300 or may be executed by the system control device200, and is not limited to either device.

From the viewpoint of reducing operational costs, it is desirable toprevent deviation that further increases the number of operations of acontrol device 300 with large power loss. In Embodiment 2, the deviationthat increases the time constant of the specific control device 300excessively can be prevented.

The power loss of the control device 300 can be obtained from the powerconverted by the control device 300 and the power loss characteristic ofthe control device 300. The power loss characteristic is, for example, arelationship between power to be converted and power loss to begenerated at that time. In general, it is represented by a quadraticfunction ap2+bp+c(a>0, c>0) of the power p to be converted; therefore,the power loss increases as the power to be converted increases.

A method of calculating the device rank of the device rank calculationunit 3 will be described. In the device rank calculation unit 3, as inEmbodiment 1, the device rank is calculated for each of the controldevices 300 in the case where it is determined that hunting has occurredeven in one device, and in the case where it is determined that nohunting has occurred even in one device, respectively. In the following,it is assumed that the power loss of the control device j at the currenttime T is p(j).

First, in the case where it is determined that hunting has occurred inone or more of the control device 300, the highest priority is tosuppress hunting. To this end, the time constant of the control device300 need be increased. The control devices 300 are ranked in the orderin which power loss p(j) is in descending order, and giving the priorityto the control device 300 having higher rank, the time constant isincreased; therefore, it is expected that the deviation which furtherincreases the power loss of the control device 300 having a large powerloss p(j) is prevented while suppressing the hunting.

Next, consider a case where it is determined that no hunting hasoccurred in one or more control devices 300. In this case, it isdesirable to decrease the time constant as small as possible in therange where no hunting occurs. The control devices 300 are ranked in theorder in which power loss p(j) is in ascending order, and giving thepriority to the control device 300 having higher rank, the time constantis decreased; therefore, it is expected that increase in the power lossp(j) occurs readily and, in the whole system, suppression in increase inthe power loss p(j).

A method of system control employed in the system control device 200according to Embodiment 2 will be described with reference to FIG. 1,FIG. 2, FIG. 6, FIG. 7, and FIG. 8.

FIG. 6 is a flowchart illustrating a flow of processes for adjustmenttime constant calculation of the system control device 200 according toEmbodiment 2. In Embodiment 2, the adjustment time constant iscalculated taking the power loss into consideration.

FIG. 7 is a flowchart illustrating a flow of processes until a process acontrol device 300 according to Embodiment 2 transmits the deviceinformation to the system control device 200.

FIG. 8 is a flowchart illustrating a flow of processes from a processafter the control device 300 according to Embodiment 2 receives theadjustment time constant from the system control device 200.

In the flowcharts of FIG. 6, FIG. 7, and FIG. 8, for Steps S102 to S105and Steps S108 to S114 in the flowchart shown in FIG. 2 of Embodiment 1,the same processing as in Embodiment 1 are used; therefore, the samereference numerals as those in FIG. 2 are attached, and the processes inStep S201, Step S206, and Step S207 are different from those inEmbodiment 1.

In Step S101 of Embodiment 1, the control device 300 stores the controlhistory and the deterioration progress degree in the device informationstorage unit 6. Whereas, in Step S201 of Embodiment 2, the controldevice 300 stores the control history and the power loss in the deviceinformation storage unit 6. Here, although the power loss is stored bythe control device 300 side, Embodiment 2 is not limited thereto, andcontrol may be performed so that the system control device 200calculates from information such as the control history.

Next, in Step S106 of Embodiment 1, the device rank calculation unit 3ranks the control devices 300 in the order of progression of thedeterioration progress degree. Whereas, in Step S206 of Embodiment 2,the device rank calculation unit 3 ranks the control devices 300 in theorder of larger power loss.

In Step S107 of Embodiment 1, the device rank calculation unit 3 ranksthe control devices 300 in the reversed order of progression of thedeterioration progress degree. Whereas, in Step S207 of Embodiment 2,the device rank calculation unit 3 ranks the control devices 300 in theorder of smaller power loss. As described in Embodiment 1, ranking isnot limited, and any method can be employed that controls to increasethe time constant of the control device 300 having a larger power lossand to decrease the time constant of the control device 300 having asmaller power loss.

As described above, in Embodiment 2, the power loss of the controldevice 300 is stored in the device information storage unit 6, and thedevice rank calculation unit 3 ranks the control devices 300 based onthe power loss of each control device 300. The time constant calculationunit 4 calculates the time constant of each control device 300 based onthe calculated device order. In Embodiment 2, the parts different fromEmbodiment 1 have been described. The other parts are the same as inEmbodiment 1. Accordingly, in the whole system, deviation in power lossis suppressed while suppressing hunting in each control device 300.

Embodiment 3

FIG. 9 is a block diagram illustrating one configuration example of asystem control device 200 according to Embodiment 3. Embodiment 3differs from other Embodiments in that the power transmission anddistribution system 100 includes a power consumption facility 400 and apower generation facility 500 and that a power loss estimation value iscalculated. In FIG. 9, the same components as those in Embodiment 1illustrated in FIG. 1 are denoted by the same reference numerals, anddetailed description thereof is omitted.

In addition to the configuration illustrated in FIG. 1, the powertransmission and distribution system 100 according to Embodiment 3includes the power consumption facility 400 including a consumed powermeasurement unit 10 and a consumed power transmission unit 11, the powergeneration facility 500 including a generated power measurement unit 12and a generated power transmission unit 13, a consumed and generatedpower reception unit 14 that receives information such as the powerconsumed by the system control device 200 in the power consumptionfacility 400 and the power generated in the power generation facility500 such as solar power generation, and a device information estimationunit 15 that estimates the power loss when the time constant of thecontrol device 300 is changed based on information of the control device300, the power consumption facility 400, and the power generationfacility 500.

The power consumption facility 400 indicates, for example, a house orfactory that consumes power. The power generation facility 500indicates, for example, a photovoltaic power generation system. Theconsumed power measurement unit 10 measures the consumed power consumedby the power consumption facility 400.

The consumed power transmission unit 11 transmits the consumed powermeasured by the consumed power measurement unit 10 to the system controldevice 200. The generated power measurement unit 12 measures the powergenerated in the power generation facility 500. The generated powertransmission unit 13 transmits the generated power measured by thegenerated power measurement unit 12 to the system control device 200.The consumed and generated power reception unit 14 receives the consumedpower transmitted from each power consumption facility 400 and thegenerated power transmitted from each power generation facility 500.

The device information estimation unit 15 calculates an estimated valueof the power loss of the entire system based on the device informationreceived by the device information reception unit 1 and the consumedpower and generated power received by the consumed and generated powerreception unit 14.

In the following, it is assumed that the time constant of the controldevice j at the current time T is c(j). When only for the control devicej′, the time constant is set to c(j′)+C by increasing, from the timeconstant c(j′) by predetermined time C seconds and for the controldevice j other than j′, the time constant c(j) is set, the power lossestimation value for the entire transmission and distribution system isset to p(j′,C). Also, when only for the control device j′, the timeconstant is set to c(j′)-C by decreasing, from the time constant c(j′)by the predetermined time C seconds and for the control device j otherthan j′, the time constant c(j) is set, the power loss estimation valuefor the entire transmission and distribution system is set to p(j′,−C).

In the device information estimation unit 15, the power loss estimationvalue p(j′,C) and the power loss estimation value p(j′,−C) arecalculated for each control device 300, and the values are used in rankcalculation by the device rank calculation unit 3. Regarding thecalculation of the power loss estimation value of the entire system, forexample, the power loss is calculated by power flow calculation, whichis a known calculation method, for the entire system based on thegenerated power and the consumed power.

Due to the change in the configuration, the method of calculating thedevice rank by the device rank calculation unit 3 is different fromthose in Embodiments 1 and 2. The device rank calculation unit 3calculates rank order for determining determine the time constants ofrespective control devices 300 so that the power loss is reduced whilesuppressing the hunting of each control device 300 based on the deviceinformation received by the device information reception unit 1 adetermination result of the hunting determination unit 2, and the powerloss estimation value calculated by the device information estimationunit 15.

First, in the case where it is determined that hunting has occurred inone or more of the control devices 300, the highest priority is tosuppress hunting. To this end, the time constant of the control device300 need be increased. The device rank calculation unit 3 calculates therank order of the control devices 300 so that the power loss estimationvalues p′(j′,C) are in the ascending order, based on the power lossestimation values p′(j′,C) calculated by the device informationestimation unit 15.

Next, the time constant calculation unit 4 calculates the time constantof each control device 300 based on the determination result of thehunting determination unit 2 and the rank order for determining the timeconstant of each control device 300 calculated by the device rankcalculation unit 3. When hunting has occurred, the time constant of thecontrol device 300 having the highest device rank is increased by thepredetermined time C seconds. Giving the priority to the control device300 having the higher rank, the time constant is increased; therefore,the power loss is reduced while the hunting is suppressed. That is, theadjustment time constant is calculated by increasing the time constantof the control device when the power estimation value is the smallest bythe predetermined time C seconds. Although the smallest is the casehere, it is not limited thereto, and any case as long as it becomessmaller may be applied.

Next, consider a case where it is determined that no hunting hasoccurred in one or more control devices 300. In this case, it isdesirable to decrease the time constant as small as possible in therange where no hunting occurs. The device rank calculation unit 3calculates the rank order of the control devices 300 so that the powerloss estimation values p′(j′,−C) are in the ascending order, based onthe power loss estimation values p′(j′,−C) calculated by the deviceinformation estimation unit 15.

Next, the time constant calculation unit 4 calculates the time constantof each control device 300 based on the determination result of thehunting determination unit 2 and the rank order for determining the timeconstant of each control device 300 calculated by the device rankcalculation unit 3. When no hunting has occurred, the time constant ofthe control device 300 having the highest device rank is decreased bythe predetermined time C seconds. Giving the priority to the controldevice 300 having the higher rank, the time constant is decreased;therefore, the power loss can be reduced. That is, the adjustment timeconstant is calculated by decreasing the time constant of the controldevice when the power estimation value is the smallest by thepredetermined time C seconds. Although the smallest is the case here, itis not limited thereto, and any case as long as it becomes smaller maybe applied.

A method of system control employed in the system control device 200according to Embodiment 3 will be described with reference to FIG. 10,FIG. 11, FIG. 12, FIG. 13, and FIG. 14.

FIG. 10 is a flowchart illustrating a flow of processes for adjustmenttime constant calculation of the system control device 200 according toEmbodiment 3. In Embodiment 3, the adjustment time constant iscalculated taking the power loss estimation value in a powertransmission and distribution system including a power consumptionfacility and a power generation facility into consideration.

FIG. 11 is a flowchart illustrating a flow of processes until a processthe power consumption facility 400 according to Embodiment 3 transmitsconsumed power to the system control device 200.

FIG. 12 is a flowchart illustrating a flow of processes until a processthe power generation facility 500 according to Embodiment 3 transmitsgenerated power to the system control device 200.

FIG. 13 is a flowchart illustrating a flow of processes until a processthe control device 300 according to Embodiment 3 transmits deviceinformation to the system control device 200.

FIG. 14 is a flowchart illustrating a flow of processes from a processafter the control device 300 according to Embodiment 3 receives anadjustment time constant from the system control device 200.

In the power consumption facility 400, a consumed power measurement unit10 measures the consumed power of the power consumption facility 400 andoutputs the consumed power to a consumed power transmission unit 11(Step S301). The consumed power transmission unit 11 acquires themeasured consumed power and transmits the consumed power to the systemcontrol device 200 (Step S302).

In the power generation facility 500, the generated power measurementunit 12 measures the generated power of the power generation facility500 and outputs the generated power to the generated power transmissionunit 13 (Step S303). The generated power transmission unit 13 acquiresthe measured generated power and transmits the measured generated powerto the system control device 200 (Step S304).

In the control device 300, the control device 300 stores the controlhistory in the device information storage unit 6 (Step S305). The deviceinformation transmission unit 7 acquires the stored device informationand transmits the information to the system control device 200 (StepS306).

Next, in the system control device 200, the consumed and generated powerreception unit 14 receives the consumed power transmitted from eachpower consumption facility 400 and the generated power transmitted fromeach power generation facility 500, and outputs the received informationon the consumed power and generated power to the device informationestimation unit 15 (Step S307). The device information reception unit 1receives the device information transmitted from each control device300, and outputs the received device information to the deviceinformation estimation unit 15, the hunting determination unit 2, andthe device rank calculation unit 3 (Step S308).

The device information estimation unit 15 acquires the consumed power,the generated power, the device information, and based on the acquiredinformation, calculates the power loss estimation value when the timeconstant of a certain control device 300 is increased by a certain timeand the power loss estimation value when the time constant of a certaincontrol device 300 is decreased by a certain time for each controldevice 300, and outputs the estimation result to the device rankcalculation unit 3 (Step S309).

The hunting determination unit 2 acquires device information, determineswhether or not hunting has occurred in each control device 300 based onthe acquired device information, and outputs the determination result tothe device rank calculation unit 3 and the time constant calculationunit 4 (Step S310).

The device rank calculation unit 3 acquires the device information andhunting determination result (Step S311), and when the huntingdetermination result indicates that hunting has occurred in one or morecontrol devices 300, based on the acquired estimation result, calculatesthe power loss estimation value p′(j′,C) when the time constant of acontrol device 300 is increased by a certain time for each controldevice, and ranks the control devices 300 in the order in which thepower loss estimation values p′(j′,C) are in ascending order (StepS312).

Meanwhile, when the hunting determination result indicates that nohunting has occurred in one or more control devices 300, based on theacquired estimation result, the device rank calculation unit 3calculates the power loss estimation value p′(j′,−C) when the timeconstant of a control device 300 is decreased by a certain time for eachcontrol device, and ranks the control devices 300 in the order in whichthe power loss estimation values p′(j′,−C) are in ascending order (StepS313). The device rank calculation unit 3 outputs the device rank to thetime constant calculation unit 4 (Step S314).

The time constant calculation unit 4 acquires the hunting determinationresult and the device rank (Step S315), and when the huntingdetermination result indicates that hunting has occurred in one or moredevices, increases the time constant of the control device 300 havingthe highest device rank by a predetermined time (Step S316). Here,“having the highest device rank” means the smallest power lossestimation value.

Meanwhile, when the hunting determination result indicates that nohunting has occurred in all the control devices 300, the time constantcalculation unit 4 decreases the time constant of the control device 300having the highest device rank by a predetermined time (Step S317). Thetime constant calculation unit 4 outputs the time constant of eachcontrol device 300 to the time constant transmission unit 5. The timeconstant transmission unit 5 acquires the time constant of each controldevice 300, and transmits the time constant to each control device 300to have the time constant updated (Step S318). Here, “having the highestdevice rank” means the smallest power loss estimation value.

Finally, in the control device 300, the time constant reception unit 8receives the time constant transmitted from the system control device200, and outputs the received time constant to the time constantadjustment unit 9 (Step S319). The time constant adjustment unit 9acquires the time constant, and updates the time constant of the controldevice 300 based on the acquired time constant (Step S320).

As described above, in Embodiment 3, the power consumption facility 400includes the consumed power measurement unit 10 and the consumed powertransmission unit 11. The power generation facility 500 includes thegenerated power measurement unit 12 and the generated power transmissionunit 13. Then, the system control device 200 receives information on thepower consumed by the power consumption facility 400 and the powergenerated by the power generation facility 500 such as photovoltaicpower generation in the consumed and generated power reception unit 14.

The device information estimation unit 15 estimates the power loss ofthe entire power transmission and distribution system 100 when the timeconstant of the control device 300 is changed based on the informationof the control device 300, the power consumption facility 400, and thepower generation facility 500. The device rank calculation unit 3calculates the rank order for determining the time constant of thecontrol device 300 based on the power loss estimation value calculatedby the device information estimation unit 15.

Accordingly, adjustment of the time constant of each control device 300so as to reduce the power loss based on the power loss estimation valueof the entire power transmission and distribution system 100 is ensuredwhile suppressing hunting of each control device 300. In Embodiment 3,the parts different from Embodiment 1 have been described. The otherparts are the same as in Embodiment 1.

Embodiment 4

Although Embodiment 4 has the same configuration as that of FIG. 1, thedifference lies in that the time constant calculation unit 4 calculatesthe adjustment time constant based on an increase rate of thedeterioration progress degree representing how many deteriorationprogress degrees of each control devices 300 are increased from thedeterioration progress degree at a reference time. In the configurationof Embodiment 4, the device rank calculation unit 3 ranks the controldevices 300, and based on the rank order, the time constant calculationunit 4 calculates the adjustment time constant. However, Embodiment 4 isnot limited thereto, instead, the time constant calculation unit 4 maybe controlled to directly calculate the adjustment time constant basedon the increase rate of the deterioration progress degree.

In Embodiment 1, deterioration due to load deviation on a specificcontrol device 300 is suppressed from becoming fast while suppressinghunting in each control device 300, however, leveling the deteriorationprogress degrees may cause failures in multiple devices at the sametime. In Embodiment 4, by leveling the increase rates of thedeterioration progress degrees, the deterioration progress degree ofeach control device 300 takes a value close to the deteriorationprogress degree at the reference time.

Here, the deterioration progress degree at the reference time isreferred to as a deterioration progress reference value. Thedeterioration progress degree reference value is represented by thefollowing expression with an operation period from the start ofoperation to the reference time, an operation target period representedby the durable hours of the device, and a deterioration progress degreetarget value represented by the deterioration progress degree when theoperation target period from the start of operation has elapsed.Deterioration progress degree reference value=(Operationperiod/Operation target period)×Deterioration progress degree targetvalue

The reference time may be the time when the deterioration progressdegree reference value is calculated, and is not limited. The referencevalue is a reference time for observing the increase rate in thedeterioration progress degree; therefore it is not limited thereto andmay be a predetermine time as long as it is set before the deteriorationprogress degree is acquired when the hunting determination unit 2determines the hunting. Further, the deterioration progress degreetarget value refers to the deterioration progress degree when thecontrol device 300 has passed the operation target period, and it is notlimited and may be an actual measurement value of the control device 300or a predicted value.

When at the start of operation, the operation period is 0, so thedeterioration progress degree reference value is 0. When X % of theoperation target period has elapsed from the start of operation, theoperation period is (X/100)×operation target period, therefore, thedeterioration progress degree reference value is (X/100)×deteriorationprogress degree target value. Further, when the operation target periodhas elapsed from the start of operation, the operation period becomesequal to the operation target period, therefore, the deteriorationprogress degree reference value becomes equal to the deteriorationprogress degree target value.

Further, the increase rate of the deterioration progress degree isdefined by the following expression with the deterioration progressdegree, the deterioration progress degree reference value, and thedeterioration progress degree target value. Increase rate of thedeterioration progress degree=(deterioration progressdegree-deterioration progress degree reference value)/deteriorationprogress degree target value. The increase rate of the deteriorationprogress degree refers to the increase rate from the deteriorationprogress degree reference value. Further, the deterioration progressdegree in this calculation formula is acquired when the huntingdetermination unit 2 determines hunting. That is, the deteriorationprogress degree in this calculation formula means the deteriorationprogress degree at the time when hunting determination is performed.

The calculation of deterioration progress degree reference value and theincrease rate may be executed by the control device 300 or may beexecuted by the system control device 200 by storing the operation starttime, the operation target period, and the deterioration progress degreetarget value in the device information storage unit 6, and is notlimited to either device. If the operation start time of each controldevice 300 is shifted or the operation target period is shifted, failurein a plurality of devices at the same time can be prevented.

A method of calculating the device rank by the device rank calculationunit 3 will be described. In the device rank calculation unit 3, as inEmbodiment 1, the device rank is calculated for each of the controldevices 300 in the case where it is determined that hunting has occurredeven in one device, and in the case where it is determined that nohunting has occurred even in one device, respectively. Hereinafter, thedeterioration progress degree target value of the control device j isset to t(j), the deterioration progress degree of the control device jat time T when hunting determination is performed is set to d(j), andthe deterioration progress degree reference value is set to r(j).

First, in the case where it is determined that hunting has occurred inone or more of the control device 300, the highest priority is tosuppress hunting. To this end, the time constant of the control device300 need be increased. The control devices 300 are ranked so that(d(j)−r(j))/t(j), which is the increase rate of the deteriorationprogress degree, is in the descending order, that is, the order ofincrease rates of deterioration progress degrees are in the descendingorder. Giving the priority to the control device having the higher rank,the time constant is increased; therefore, it is expected that(d(j)−r(j))/t(j) will be suppressed from being increased while thehunting is suppressed, and the increase rates will be leveled.

Next, consider a case where it is determined that no hunting hasoccurred in one or more control devices 300. In this case, it isdesirable to decrease the time constant as small as possible in therange where no hunting occurs. The control devices 300 are ranked sothat (d(j)−r(j))/t(j), which is the increase rate of each deteriorationprogress degree, are in the ascending order, that is, the order ofincrease rate of deterioration progress degrees are in the ascendingorder. Giving the priority to the control device 300 having the higherrank, the time constant is decreased; therefore, it is expected that thetime constant is prevented from being excessively large, and(d(j)−r(j))/t(j) will be leveled.

A method of system control employed in the system control device 200according to Embodiment 4 will be described with reference to FIG. 1,FIG. 2, FIG. 15, and FIG. 16. The parts different from Embodiment 1 willbe described. In the flowcharts of FIG. 15, and FIG. 16, for Steps S102to S105 and Steps S108 to S114 in the flowchart shown in FIG. 2 ofEmbodiment 1, the same processing as in Embodiment 1 are used;therefore, the same reference numerals as those in FIG. 2 are attached,and the processes in Step S401, Step S406, and Step S407 are differentfrom those in Embodiment 1.

FIG. 15 is a flowchart illustrating a flow of processes until a processthe control device 300 according to Embodiment 4 transmits deviceinformation to the system control device 200. In Step S101 of Embodiment1, the control device 300 stores the control history and thedeterioration progress degree in the device information storage unit 6.Whereas, in Step S401 of Embodiment 2, the control device 300 stores thecontrol history, the operation period, the operation target period, thedeterioration progress degree target value, the deterioration progressdegree, the deterioration progress degree reference value, and theincrease rate from the deterioration progress degree reference value(=(deterioration progress degree-deterioration progress degree referencevalue)/deterioration progress degree target value) in the deviceinformation storage unit 6. Here, although the above increase rate isstored by the control device 300 side, Embodiment 4 is not limitedthereto, and control may be performed so that the system control device200 calculates thereof.

FIG. 16 is a flowchart illustrating a flow of processes for adjustmenttime constant calculation of the system control device 200 according toEmbodiment 4. In Embodiment 4, the adjustment time constant iscalculated taking the ratio of the difference between the deteriorationprogress degree and the deterioration progress degree reference value tothe deterioration progress degree target value into consideration. InEmbodiment 4, although the ratio to the deterioration progress degreetarget value is referenced, Embodiment 4 is not limited thereto, andwhen the increase rate between the control devices 300 can be comparedbased on the difference between the deterioration progress degree andthe deterioration progress degree reference value, the difference alonemay be applicable.

In Step S106 of Embodiment 1, the device rank calculation unit 3 ranksthe control devices 300 in the order of progression of the deteriorationprogress degree. Whereas, in step S406 of Embodiment 4, the device rankcalculation unit 3 ranks the control devices 300 so that the increaserates of the deterioration progress degrees are in the descending order.As in Embodiment 1, the ranking is an example, and control may beapplicable in which the time constant calculation unit 4 calculates anadjustment time constant in which the time constant of the controldevice 300 having a large increase rate of deterioration progress degreeis increased without calculating the ranking. In this case, it is evenmore preferable to select the control device 300 having the largestincrease rate of the deterioration progress degree and control tocalculate the adjustment time constant.

In Step S107 of Embodiment 1, the device rank calculation unit 3 ranksthe control devices 300 in the reversed order of progression of thedeterioration progress degree. Whereas, in step S407 of Embodiment 4,the device rank calculation unit 3 ranks the control devices 300 so thatthe increase rates of the deterioration progress degrees are in theascending order. As in Embodiment 1, the ranking is an example, andcontrol may be applicable in which the time constant calculation unit 4calculates the adjustment time constant in which the time constant ofthe control device 300 having a small increase rate of deteriorationprogress degree is decreased without calculating the ranking.

As described in Embodiment 1, the ranking by the device rank calculationunit 3 is not limited. Any control method can be employed as long as thetime constant of the control device 300 having a large increase rate ofthe deterioration progress degree is increased and the time constant ofthe control device 300 having a small increase rate of the deteriorationprogress degree is decreased.

As described above, in Embodiment 4, the deterioration progress degreetarget value, the deterioration progress degree, and the deteriorationprogress degree reference value of the control device 300 are stored inthe device information storage unit 6 in advance, the device rankcalculation unit 3 ranks the control devices 300 based on the increaserate of the deterioration progress degree of each control device 300(=(deterioration progress degree-deterioration progress degree referencevalue)/deterioration progress degree target value).

The time constant calculation unit 4 calculates the adjustment timeconstant of each control device 300 based on the calculated device rank.Specifically, the adjustment time constant in which the time constant ofthe control device 300 having a larger increase rate is increased iscalculated and the time constant of the control device 300 having asmaller increase rate is decreased is calculated.

In Embodiment 4, the parts different from Embodiment 1 have beendescribed. The other parts are the same as in Embodiment 1. Accordingly,in the whole system, the increase rates of the deterioration progressdegrees will be leveled while suppressing hunting in each control device300, and failure in a plurality of devices at the same time can beprevented.

The foregoing configurations of Embodiments are configuration examplesof the present invention. It should be noted that Embodiments of thepresent invention can be arbitrarily combined and can be appropriatelymodified or omitted without departing from the scope of the invention.

EXPLANATION OF REFERENCE SIGNS

1 device information reception unit, 2 hunting determination unit, 3device rank calculation unit, 4 time constant calculation unit, 5 timeconstant transmission unit, 6 device information storage unit, 7 deviceinformation transmission unit, 8 time constant reception unit, 9 timeconstant adjustment unit, 10 consumed power measurement unit, 11consumed power transmission unit, 12 generated power measurement unit,13 generated power transmission unit, 14 consumed and generated powerreception unit, 15 device information estimation unit, 100 powertransmission and distribution system, 200 system control device, 300control device, 400 power consumption facility, 500 power generationfacility

1-15. (canceled)
 16. A system control device, comprising: a processor toexecute a program; an output interface; and a memory to store theprogram which, when executed by the processor, performs processes of,determining whether hunting has occurred or not for each of controldevices in a power transmission and distribution system based on acontrol history of the control devices; calculating an adjustment timeconstant in accordance with state information of the control device,which is any one type of information among a hunting determinationresult of whether hunting has occurred or not, a deterioration progressdegree indicating a progress degree of deterioration of the controldevice, an increase rate of a deterioration progress degree indicatinghow many the deterioration progress degrees of the control device haveincreased from the deterioration progress degree at a reference time,and a power loss of the control device and a power loss estimation valueof the control device; and transmitting the adjustment time constant tothe control device through the output interface.
 17. The system controldevice according to claim 16, wherein the state information includes anyof the deterioration progress degree, the increase rate of thedeterioration progress degree, and the power loss, and when theprocessor determines that the hunting has occurred in one or more of thecontrol devices, the processor calculates the adjustment time constantin which a time constant of the control device having the stateinformation with a highest significance level is increased.
 18. Thesystem control device according to claim 17, wherein, the stateinformation includes any of the deterioration progress degree, theincrease rate of the deterioration progress degree, and the power loss,and when the processor determines that no hunting has occurred in one ormore of the control devices, the processor calculates the adjustmenttime constant in which the time constant of the control device havingthe state information with a low significance level is decreased. 19.The system control device according to claim 16, wherein, the stateinformation includes any of the deterioration progress degree, theincrease rate of the deterioration progress degree, and the power loss,and when the processor determines that the hunting has occurred in oneor more of the control devices, the processor calculates the adjustmenttime constant in which a time constant of the control device having thestate information with a highest significance level is increased. 20.The system control device according to claim 19, wherein, the stateinformation includes any of the deterioration progress degree, theincrease rate of the deterioration progress degree, and the power loss,and when the processor determines that no hunting has occurred in one ormore of the control devices, the processor calculates the adjustmenttime constant in which a time constant of the control device having thestate information with a lowest significance level is decreased.
 21. Thesystem control device according to claim 16, further comprising: aninput interface to receive consumed power of a power consumptionfacility included in the power transmission and distribution system andgenerated power of a power generation facility included in the powertransmission and distribution system, wherein the state information isthe power loss estimation value, the processor estimates the power losswhen the time constant is increased by a predetermined time for each ofthe control devices and calculates respective power loss estimationvalues based on the generated power, the consumed power, and the deviceinformation, and when the processor determines that the hunting hasoccurred in one or more of the control devices, the processor calculatesthe adjustment time constant by increasing the time constant of thecontrol device when the power loss estimation value is decreased by thepredetermined time.
 22. The system control device according to claim 21,wherein the processor estimates the power loss when the time constant isdecreased by a predetermined time for each of the control devices andcalculate respective power loss estimation values based on the generatedpower, the consumed power, and the device information, and when theprocessor determines that no hunting has occurred in one or more of thecontrol devices, the processor calculates the adjustment time constantby decreasing the time constant of the control device when the powerloss estimation value is decreased by the predetermined time.
 23. Thesystem control device according to claim 16, wherein, the stateinformation includes any of the deterioration progress degree, theincrease rate of the deterioration progress degree, and the power loss,and every time a time constant of the control device is updated with theadjustment time constant, the processor determines whether the huntinghas occurred or not, every time the processor determines that thehunting has occurred in one or more of the control devices, theprocessor calculates the adjustment time constant in which the timeconstants of the control devices are increased in an order of thecontrol devices having the state information with a high significancelevel, and every time the adjustment time constant is calculated, theprocessor transmits the calculated adjustment time constant to thecorresponding control device and has the time constant of the controldevice updated.
 24. The system control device according to claim 23,wherein, every time the processor determines that no hunting hasoccurred in one or more of the control devices, the processor calculatesthe adjustment time constant in which the time constants of the controldevices are decreased in an order of the control devices having thestate information with a low significance level.
 25. A method of systemcontrol, comprising: determining whether hunting has occurred or not foreach of control devices in a power transmission and distribution systembased on a control history of the control devices; calculating anadjustment time constant in accordance with state information of thecontrol device, which is any one type of information among a huntingdetermination result of whether hunting has occurred or not, adeterioration progress degree indicating a progress degree ofdeterioration of the control device, an increase rate of a deteriorationprogress degree indicating how many the deterioration progress degreesof the control device have increased from the deterioration progressdegree at a reference time, and a power loss of the control device and apower loss estimation value of the control device; and transmitting theadjustment time constant to the control device.